1. Field of the Invention
The present invention relates generally to a Flat Fluorescent Lamp (FFL), and, more particularly, to an FFL that ensures a sufficient light emission area, thereby improving the uniformity of light emission and a luminance characteristic. Furthermore, the present invention relates to a Liquid Crystal Display (LCD) using the FFL.
2. Description of the Related Art
Cold-Cathode Fluorescent Lamps (CCFLS) are mainly used as lamps for various illumination devices or displays. Such CCFLs are classified into Internal Electrode Fluorescent Lamps (IEFLS) and External Electrode Fluorescent Lamp (EEFLS) according to the location of the electrodes. In IEFLs, electrodes are installed inside sealed glass tubes containing discharge gas and gaseous mercury, and fluorescent material is applied to the inside surfaces of the glass tubes. In contrast, in EEFLs, electrodes are installed outside glass tubes, and fluorescent material is applied to the inside surfaces of the glass tubes.
When high-frequency Alternating Current (AC) signals are applied to the internal electrodes of an IEFL, an electric field is generated between the electrodes, therefore plasma discharge occurs. Electrons, which are generated during the discharge, excite mercury, and ultraviolet rays are generated. Fluorescent material is excited and undergoes a transition due to the ultraviolet rays, thus resulting in the generation of visible rays.
In contrast, when high-frequency AC signals are applied to the external electrodes of an EEFL, plasma discharges are generated between positive electrodes inside a glass tube, electrons are generated, mercury is excited by the electrons, and finally fluorescent material emits light. The EFFL has advantages in that the amount of heat is low and the EFFL can be driven at high efficiency because wall charges are formed on the inside surface of a glass tube near the electrodes due to plasma discharge and subsequent plasma discharge is generated at relatively low voltage using the wall charges, and a plurality of EFFLs can be driven using a single inverter because the voltage drop is very small.
Meanwhile, an LCD displays images by adjusting the transmissivity of liquid crystal cells in response to video signals. An active matrix LCD has an advantage in its ability to display moving images because individual switching elements are formed for respective liquid crystal cells. Thin Film Transistors (hereinafter referred to as “TFTs”) are chiefly used as the switching elements.
An LDC is not a self-emissive device, therefore it requires a separate backlight unit. Conventional backlight units for LCDs are classified into edge light-type backlight units, each of which converts light, radiated from a lamp located at one end thereof, into surface light using a light guide plate, and radiates the surface light onto an LCD panel, and direct light-type backlight units, each of which radiates light onto an LCD panel using a plurality of lamps located under the LCD panel.
Recently, research and development into light source devices, which have light emission efficiency, luminance, and uniformity of luminance greater than those of existing edge light type backlight units or existing direct light type backlight units, is being actively conducted.
FIG. 1 is a diagram showing the schematic structure of a conventional light source device. Referring to FIG. 1, the light source device includes a front transparent substrate 1 and a rear substrate 1, partitions 4 configured to form plasma discharge channels 8 between the front transparent substrate 1 and the rear substrate 2, fluorescent material 5 applied to the insides of the plasma discharge channels 8, and electrodes 3a and 3b formed on the outside surfaces of the rear substrate 2 and configured to have opposite polarities. An insulating layer 7 is further provided on the electrode 3a formed on top of the rear substrate 2, and electrically insulates the electrode 3a. 
The electrodes 3a and 3b may be formed in the sides of the plasma discharge channels 18 so that they are opposite each other.
Inert gases, that is, argon (Ar), neon (Ne) and xenon (Xe), along with gaseous mercury (Hg), are uniformly injected into the plasma discharge channels 8.
The partitions 4 have a height ranging from several mm to tens of mm, and functions to form plasma discharge channels 8 between the front transparent substrate 1 and the rear substrate 12. Furthermore, both side surfaces of each partition 14 are formed to have slopes, or are curved to have curvature, therefore light is reflected therefrom, thereby increasing the light emission area.
The fluorescent material 5 functions to emit light by mercury excited by electrons generated by plasma discharges, and to radiate visible rays.
AC voltage is applied to the electrodes 3a and 3b so that electric discharge occurs in the plasma discharge channels 8.
A glass frame 9 is disposed between the front transparent substrate 1 and the rear substrate 2 along the edge of the light source device, and the glass frame 9 is attached to the front transparent substrate 1 and the rear substrate 2 using a sealant.
FIG. 2 is an enlarged view of a conventional partition, shown in region A of FIG. 1. Meanwhile, in FIG. 2, the illustration of the fluorescent material 5 is omitted for ease of understanding of a light path.
Referring to FIG. 2, since the top surface of the conventional partition 4 is formed to have no curvature, a dark region D is created. As a result, there is a problem in that uniform light emission and luminance cannot be achieved throughout the entire surface of an light source device.